During the mobile communication, it is necessary for all users to share limited wireless resources, so as to enable different users to perform the communication at different locations simultaneously and reduce interference as possible. A multiple-access technique has been presented to achieve this object. Along with the rapid development of the mobile communication technology, there is an explosive growth in the amount of users and services, resulting in more demands on a system capacity of a wireless network. Due to the explosive growth in the amount of users, the multiple-access technique has become a crucial issue for network updating. The multiple-access technique may device a basic capacity of the network, and may significantly affect the system complexity and the deployment cost.
For a mobile communication system in the related art, a multiplexing function for multiple users may be achieved through an orthogonal mode. For example, a Frequency Division Multiple Access (FDMA) technique is adopted by a 1st-Generation (1G) mobile communication system, a Time Division Multiple Access (TDMA) technique is adopted by a 2nd-Generation (2G) Global System for Mobile communication (GSM) system, a Code Division Multiple Access (CDMA) technique is adopted by a 3rd-Generation communication system, and an Orthogonal Frequency Division Multiplexing (OFDM) technique is adopted by a 4th-Generation (4G) mobile communication system. As an advantage of the orthogonal mode, the interference among the multiple users is relatively small, but as its disadvantage, the capacity may be limited to the number of orthogonal samples.
Sparse Code Multiple Access (SCMA) technique is a superposition technique based on a sparse codebook, i.e., a channel may be further multiplexed by multiple users on an existing time-frequency resource, and the multiple users may be differentiated from each other through a superposed codebook. For the SCMA technique, encoding modes corresponding to different users may have an identical diversity order. However, with respect to a construction method of Low Density Parity Check (LDPC) codes, in the case that the encoding modes corresponding to the multiple users have the same diversity order, it is difficult to improve the multiuser detection performance.